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An Adaptive Dual-Stack QKD-PQC Framework for Secure and Reliable Inter-Site Communication

Alessio Di Santo, Walter Tiberti, Dajana Cassioli

Published Jan 1, 2025• 0 citations
OpenAlex

Abstract

The advent of quantum computing imposes unprecedented risks on conventional cryptosystems, necessitating novel secure communication strategies. This work presents a modular, hybrid, and adaptive protocol that integrates Quantum Key Distribution (QKD) with Post-Quantum Cryptography (PQC) to maintain continuous, Quantum-Safe Key Exchanges, even under adverse network conditions that typically hinder the state-of-the-art QKD-based methods. At its core are specialized Crypto-Machines, which incorporate QKD Nodes compliant with ETSI-14 standards and modular PQC components, thereby supporting seamless transitions among lattice-, hash-, or code-based schemes. A signed, Quantum-Resistant, HOTP-based mechanism ensures robust mutual authentication. When QKD utilization becomes infeasible—due to, for example, fiber tampering—the protocol dynamically shifts to PQC, safeguarding ongoing communications. Once a key is established, AES-256-GCM encryption provides strong data confidentiality. Simulations have been conducted with the SeQUeNCe toolkit to demonstrate the protocol’s adaptability and resilience. The results show how Crypto-Machines are able to provide QKD exchanges under favorable network conditions while also being able to fall-back to PQC-based approaches with a minimal impact on the performance. Hence, the proposed stack allows operators to maintain Quantum-Proof Key Exchanges where current state-of-the-art solutions are impaired by a low-quality network connection, and thereby offering a forward-looking security framework suited to the quantum era

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The advent of quantum computing imposes unprecedented risks on conventional cryptosystems, necessitating novel secure communication strategies. This work presents a modular, hybrid, and adaptive protocol that integrates Quantum Key Distribution (QKD) with Post-Quantum Cryptography (PQC) to maintain continuous, Quantum-Safe Key Exchanges, even under adverse network conditions that typically hinder the state-of-the-art QKD-based methods. At its core are specialized Crypto-Machines, which incorporate QKD Nodes compliant with ETSI-14 standards and modular PQC components, thereby supporting seamless transitions among lattice-, hash-, or code-based schemes. A signed, Quantum-Resistant, HOTP-based mechanism ensures robust mutual authentication. When QKD utilization becomes infeasible—due to, for example, fiber tampering—the protocol dynamically shifts to PQC, safeguarding ongoing communications. Once a key is established, AES-256-GCM encryption provides strong data confidentiality. Simulations have been conducted with the SeQUeNCe toolkit to demonstrate the protocol’s adaptability and resilience. The results show how Crypto-Machines are able to provide QKD exchanges under favorable network conditions while also being able to fall-back to PQC-based approaches with a minimal impact on the performance. Hence, the proposed stack allows operators to maintain Quantum-Proof Key Exchanges where current state-of-the-art solutions are impaired by a low-quality network connection, and thereby offering a forward-looking security framework suited to the quantum era
The Hybrid approach in Quantum Cryptography creates adaptable security model which provides the safest Communication in the emerging quantum era. The development of quantum computing raise questions about the long-term security. Traditional algorithms, such as RSA, ECC, and Diffie-Hellman, which is seemed computationally secure but it can be effectively solved by quantum algorithms such as Shor's and Grover's. This problem leads to the origination of two key trends in current studies, namely Post-Quantum Cryptography (PQC), designing mathematical approaches to encryption resistant to quantum attacks; Quantum Key Distribution (QKD) using the principles of quantum mechanics to assure security in communications. Accordingly, this research proposes a hybrid security framework including reliable data encryption and authentication using PQC, combined with the safe key- exchange method of QKD. The model is implemented in Python, Qiskit, and PQClean's Kyber and Dilithium algorithms to show how these two paradigms can cooperate toward quantum- resilient communication. To present the system performance, key exchange efficiency, computational overhead, and security strength have been considered. According to the results, this hybrid approach gives superior defense against quantum threats while maintaining practical effectiveness for real-world applications such as cloud security, 6G networks, and the Internet of Things.
The development of quantum computers will provide modern cryptographic systems with a practical computing infrastructure, yet the number-theoretic assumptions these systems are built on poses an acute security risk at this juncture, especially when Shor and Grover’s algorithms are considered. In this article, we present QRC-Stack (Quantum Resilient Cryptographic Stack): A modular architecture for post quantum about cyber resilient communication in current and next generation infrastructures of the internet. QRC-Stack combines lattice-based and hash-based schemes with transport layers and key management to guarantee data integrity, confidentiality, and authenticity within classical networks as well as software-defined networks. The architecture of QRC-Stack is enhanced by incorporating hybrid key exchange models that integrate classical (e.g., ECDH) and post-quantum (PQ) cryptography; Kyber and Dilithium from NIST PQC finalists to sustain legacy interoperability while advancing resilience to future threats in quantum networked environments The newly proposed QRC-Stack model includes three interrelated parts that together improve the security and flexibility of cryptographic communication within a quantum-threat context. Starting with the key management layer for quantum-aware systems (QKML), it incorporates a session key distribution system that the quantum cryptography foe cannot breach. Furthermore, the Adaptive Cipher Suite Negotiation (ACSN) injects a more node centric, risk-adaptive model in whereby selection of a cryptographic suite from a pool of available options is done dynamically where the suit best optimizes contextual threat. In addition, Q-Protect Transport Module enables seamless alignment with pre-existing transport protocols such as TLS/IPSec and QUIC or SD-WAN tunnels with limited overhead footprint. Emulation testing on SDN testbeds and active WAN environments showed that QRC-Stack sustained enterprise-class encryption throughput while adding latency overhead less than eight percent. Moreover, this hybrid architecture gives forward secrecy and stronger resistance to quantum-enhanced man-in-the-mid solar attacks with faster key refresh rates. QRC-Stack also outperformed classical TLS 1.3 alongside other variants of Transition Post Quantum Cryptography’, claiming steadfast post-compromised security while surpassing baseline models in adaptability, resilience, and versatility making it ideal for next-generation network backbone design. This information reconfirms QRC-Stack's supurb strength as an extensible multi layered blanced framework solution for communication systems in layers form situated in scenarios involving surveillance from powerful post-quantum adversaries. It helps to control the move toward safely moving quantum national, enterprise, and IoT networks from cryptographic systems built for surveillance heavy environments with minimal changes to current infrastructure.
The advent of quantum computing threatens classical cryptographic mechanisms, demanding new strategies for securing communication networks. Since real-world networks cannot be fully Quantum Key Distribution (QKD)-enabled due to infrastructure constraints, practical security solutions must support hybrid operation. This paper presents an adaptive security framework that enables quantum-safe communications across real-world heterogeneous networks by combining QKD and Post-Quantum Cryptography (PQC). Building upon a hierarchical key management architecture with Virtual Key Management Systems (vKMS) and a centralized Quantum Security Controller (QuSeC), the framework dynamically assigns security levels based on node capabilities. By transitioning between pure QKD, hybrid, and PQC modes, it ensures end-to-end quantum-safe protection regardless of the underlying node capabilities. The framework has been implemented and validated on a Kubernetes-based containerized testbed, demonstrating robust operation and performance across all scenarios. Results highlight its potential to support the gradual integration of quantum-safe technologies into existing infrastructures, paving the way toward fully quantum-safe communication networks.
The fast development of cyber communications, multimedia distribution, remote working have promoted the demand to transmit sensitive information through secure means in both the public and the private networks. The advent of massive quantum computers is rendering traditional cryptographic algorithms like RSA and Elliptic Curve Cryptography (ECC) insecure because they can crack the classical public-key algorithms like the Shor and Grover algorithms. This brings an immediate need of hybrid cryptographic systems, which integrate classical, quantum, and post-quantum algorithms to provide confidentiality, integrity, authentication, and future security beyond the quantum threat horizon.The paper is a proposal of a Hybrid Quantum-Post-Quantum Cryptographic Framework of transmitting files safely. It starts by aggregating files, which is a process to compress several files, images, videos, and multimedia files that users have chosen into one file to minimize redundancy and ease encryption. The AES-256 encrypted file is in GCM mode and provides confidentiality and integrity of the compressed file.The dual-layer mechanism ensures key establishment security. To begin with, Quantum Key Distribution (QKD) based on the protocols of BB84/E91 allows the Sender and the Receiver to generate a Quantum Secret Key (QSK) by exchanging quantum bits in quantum channel. Constant monitoring of the error rate facilitates automatic eavesdropping detection, and guarantees the keys generation is made when the conditions are secure, as well as the safeguarding of interception and man-in-the-middle attacks.A post-quantum layer is provided to ensure long-term security against quantum cryptanalysis, which uses Kyber, a NIST-approved lattice-based Key Encapsulation Mechanism (KEM). The Receiver creates a key pair of Kyber and disseminates the public key to the Sender. By using encapsulation, the Sender gets a PQC ciphertext and a Shared Secret (SS), with decapsulation on the Receiver side giving ensure that only participants of good faith get the same secret value.The hybridization phase consists of combining the QSK of QKD and SS of Kyber with the help of HKDF-SHA256 to obtain a Final Wrap Key (FWK). AES-GCM encrypts the key of file encryption by wrapping it with FWK which allows a secure and authenticated transfer of the key. The Sender sends four messages: encrypted file, Kyber ciphertext, wrapped AES key and the initialisation vector. At Receiver end, FWK is calculated once again with the help of QSK and SS so that the original data can be decrypted with the help of AES key.The suggested framework provides a defense-in-depth solution based on the combination of quantum security, post-quantum resilience and authenticated symmetric encryption. It can be analyzed that there is a strong resistance to classical and quantum adversaries, scalability, and compatibility with the existing communication networks. This renders the model to be appropriate to secure government communication, military systems, data exchange in healthcare environments, cloud storage and financial infrastructures. Keywords— Quantum Key Distribution (QKD), Post-Quantum Cryptography (PQC), Kyber,Key Encapsulation Mechanism (KEM), HKDF-SHA256, Quantum Secret Key (QSK), GCM Mode.
The emergence of quantum computing poses a threat to classical cryptography algorithms, necessitating a shift to quantum secure cryptography. Hybrid protocols combining at least one classical and one quantum-resistant cryptographic algorithm are becoming the standard for securing communications. In this work, we present our novel solution for integrating three different cryptographic assumptions (two of them quantumresistant) into hybrid network security protocols, ensuring that three different cryptographic assumptions must be broken before the protocol becomes vulnerable. Our solution allows for a seamless integration of classical and post-quantum (PQ) cryptography, and quantum key distribution (QKD) into existing network security protocols (e.g., TLS, IPsec) without any major modifications to the protocols themselves. This crypto-agility ensures the mitigation of some of the most well known challenges of both PQ cryptography and QKD. Our findings demonstrate the feasibility of such triple-hybrid network security protocols, showing non-substantial decrease in performance and almost no added packet overhead compared to state of the art protocols. In exchange, we pave the way towards next generation networks where the potential of new quantum-resistant cryptographic schemes can be leveraged in a dynamic and agile fashion, thus fostering a new era of unbreakable communication systems.
The exponential development of quantum computing represents a serious threat to the existence of the modern cybersecurity infrastructure. Fault-tolerant large-scale quantum computing will be realized roughly five to ten years hence, and will make most of the current standards for asymmetric cryptography-such as RSA and ECC-deviant. While mitigations, such as Post-Quantum Cryptography (PQC) and Quantum Key Distribution (QKD) offer possible countermeasures, both are hampered by vulnerabilities of their own. Respectively, PQC relies on unproven mathematical hardness assumptions that are always subject to future algorithmic innovations, while QKD is limited by the physical requirements of a dedicated quantum channel.This paper presents a new hybrid protocol which aims to solve these limitations by combining PQC and QKD into a unified design. The proposed scheme will hybridize the secure key resulting from the BB84-based QKD protocol with a second secret derived by using a lattice-based PQC key exchange, using a strong hybrid key derivation function. It deals with a point-to-point transport-layer model, which is in line with the technological limitations of QKD models at present. The implementation would need trusted nodes or quantum repeaters, which are beyond the reach of this implementation. The system is implemented on a dual-channel platform: the quantum channel is used for key distribution and the classical channel is used for PQC negotiation and secure data transmission, all classical communication is authenticated by HMAC. The resulting architecture is a future-proof quantum-safe communication system that will protect government sensitive data, as well as financial and e-commerce enterprises, thus ensuring the transition to a quantum resistant digital society in the face of a catastrophic event that would have a massive financial and societal impact.